Rotorcraft and method of controlling rotorcraft

ABSTRACT

According to one implementation, a rotorcraft includes a first rotorcraft and at least one second rotorcraft. The first rotorcraft has a first main rotor and a first tail rotor. The at least one second rotorcraft has a second main rotor and a second tail rotor. The at least one second rotorcraft are attachable and detachable to and from the first rotorcraft. Further, according to one implementation, a method of controlling the above-mentioned rotorcraft includes: flying the first rotorcraft, to which the at least one second rotorcraft has been attached, to a destination; and separating the at least one second rotorcraft from the first rotorcraft at the destination.

CROSS REFERENCES TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromJapanese Patent Application No. 2018-211862, filed on Nov. 12, 2018; theentire contents of which are incorporated herein by reference.

FIELD

Implementations described herein relate generally to a rotorcraft and amethod of controlling a rotorcraft.

BACKGROUND

Conventionally, a multicopter which can house slave rotorcrafts has beensuggested as a rotorcraft which can carry out missions at a plurality ofloci simultaneously (for example, refer to Japanese Patent ApplicationPublication JP2016-064768 A). A multicopter is a kind of a helicopter,and is a rotorcraft which has not less than three rotors.

Moreover, a method of remotely controlling an unmanned aircraft, whichfunctions as a slave rotorcraft, by another unmanned aircraft, whichfunctions as a master rotorcraft, through wireless communication hasalso been suggested (for example, refer to Japanese Patent ApplicationPublication JP2015-191254 A).

An object of the present invention is to provide a rotorcraft and amethod of controlling a rotorcraft which can carry out missions at locisimultaneously with easier maneuvering.

SUMMARY OF THE INVENTION

In general, according to one implementation, a rotorcraft includes afirst rotorcraft and at least one second rotorcraft. The firstrotorcraft has a first main rotor and a first tail rotor. The at leastone second rotorcraft has a second main rotor and a second tail rotor.The at least one second rotorcraft is attachable to and detachable fromthe first rotorcraft.

Further, according to one implementation, a method of controlling theabove-mentioned rotorcraft includes: flying the first rotorcraft, towhich the at least one second rotorcraft has been attached, to adestination; and separating the at least one second rotorcraft from thefirst rotorcraft at the destination.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a perspective view showing a structure of a rotorcraftaccording to an implementation of the present invention;

FIG. 2 shows the first specific example of a detachable structure shownin FIG. 1 ;

FIG. 3 shows the second specific example of the detachable structureshown in FIG. 1 ;

FIG. 4 is an enlarged longitudinal sectional view showing the thirdspecific example of the detachable structure shown in FIG. 1 ;

FIG. 5 is an enlarged longitudinal sectional view showing the detachablestructure shown in FIG. 4 in a docked state;

FIG. 6 shows an example of a structure for supplying an electric powerto a battery in each of slave rotorcrafts from a master rotorcraft shownin FIG. 1 ;

FIG. 7 shows a state where the slave rotorcraft is docked to adetachable arm of the master rotorcraft shown in FIG. 6 ;

FIG. 8 is a top view showing an example where the slave rotorcrafts ofthe rotorcraft shown in FIG. 1 are connected to the master rotorcraft atdifferent positions;

FIG. 9 shows an example in which each of the slave rotorcrafts shown inFIG. 1 is tilted relative to the master rotorcraft; and

FIG. 10 shows an example in which a second main rotor of each of theslave rotorcrafts shown in FIG. 1 is tilted relative to the slaverotorcraft.

DETAILED DESCRIPTION

A rotorcraft and a method of controlling a rotorcraft according toimplementations of the present invention will be described withreference to the accompanying drawings.

(Structure and Function of Rotorcraft)

FIG. 1 is a perspective view showing a structure of a rotorcraftaccording to an implementation of the present invention.

A rotorcraft 1 has a master rotorcraft 2 and one or more slaverotorcrafts 3 which can be attached to and detached from the masterrotorcraft 2. Although FIG. 1 shows an example in which four slaverotorcrafts 3 are coupled to the master rotorcraft 2, the number of theslave rotorcrafts 3 is flexible.

The master rotorcraft 2 is a first rotorcraft which has a first mainrotor 2A and a first tail rotor 2B. That is, the master rotorcraft 2 canfly as an independent first rotorcraft regardless of whether the slaverotorcrafts 3 are coupled to the master rotorcraft 2. Although the firsttail rotor 2B is a ducted fan surrounded by an annular duct in anexample shown in FIG. 1 , the first tail rotor 2B may have anotherstructure.

On the other hand, each of the slave rotorcrafts 3 is a secondrotorcraft which has a second main rotor 3A and a second tail rotor 3B.That is, each of the slave rotorcrafts 3 can fly as an independentsecond rotorcraft even when the slave rotorcraft 3 is not coupled to themaster rotorcraft 2.

The master rotorcraft 2 and the slave rotorcrafts 3 may be a mannedaircraft or an unmanned aircraft. Whether to make the master rotorcraft2 and the slave rotorcrafts 3 manned aircrafts or unmanned aircrafts maybe determined according to respective missions of the master rotorcraft2 and the slave rotorcrafts 3 and/or needs of a user. When each of themaster rotorcraft 2 and the slave rotorcrafts 3 is an unmanned aircraft,there is an advantage that no pilot is necessary leading to improvementsin safety, particularly in a case of a defensive purpose.

Examples of the missions of the master rotorcraft 2 and the slaverotorcrafts 3 include a checkup of an infrastructure, such as a road, arailroad, a water and sewerage, a power transmission network, a port, adam, and a communication facility, as well as transmission of voices orradio waves for broadcasting, photographing from the sky, and defensivemissions. Examples of defensive missions include a mission of loadingexplosives on some or all of the master rotorcraft 2 and the slaverotorcrafts 3 to detonate the explosives at a target area, and a missionto fly as multiple targets.

When each of the master rotorcraft 2 and the slave rotorcrafts 3 is anunmanned aircraft, the master rotorcraft 2 and each of the slaverotorcrafts 3 can be maneuvered from a remote place by wirelesslytransmitting control signals from a controller 4 having a wirelessdevice 4A to a control system 5A mounted on the master rotorcraft 2 andto a control system 5B mounted on each of the slave rotorcrafts 3 asexemplified by FIG. 1 . Alternatively, the master rotorcraft 2 and eachof the slave rotorcrafts 3 may fly on automatic pilot by installingflight programs in advance in the control system 5A mounted on themaster rotorcraft 2 and in the control system 5B mounted on each of theslave rotorcrafts 3.

An engine 6, such as a reciprocating engine or a gas turbine engine, ormotors 7 may be used to rotate the first main rotor 2A and the firsttail rotor 2B of the master rotor craft 2 and to rotate the second mainrotors 3A and the second tail rotors 3B of the slave rotorcrafts 3.Alternatively, both of the engine 6 and the motors 7 are used to rotatethe first main rotor 2A and the first tail rotor 2B of the masterrotorcraft 2 and to rotate the second main rotors 3A and the second tailrotors 3B of the slave rotorcrafts 3. As a practical example, the motors7 may be rotated using the power of the engine 6, and all of the rotorsmay be rotated using the motors 7.

In general, as the rotorcraft becomes larger, an engine that is largeenough to generate a large amount of power must be mounted on therotorcraft. On the contrary, as the rotorcraft becomes smaller, anelectric-powered rotorcraft that is easy to maintain is adopted.

Accordingly, with respect to the master rotorcraft 2 to which the slaverotorcrafts 3 are coupled, it is practical to use, as the masterrotorcraft 2, a large-sized rotorcraft in which the first main rotor 2Aand the first tail rotor 2B are rotated using the engine 6 asexemplified in FIG. 1 . As a matter of course, the engine 6 may be usedto rotate the motors 7, and the motors 7 may be used to rotate the firstmain rotor 2A and the first tail rotor 2B as mentioned above.

On the contrary, for each of the slave rotorcrafts 3, it is practical touse, as the slave rotorcraft 3, a small-sized rotorcraft in which theelectric second main rotor 3A and the electric second tail rotor 3B arerotated using only the motor 7 and without using the engine 6.

In this case, each of the slave rotorcrafts 3 includes a battery 8 thatsupplies electric power to the motor 7 to rotate the second main rotor3A and the second tail rotor 3B. Thus, at least one of a battery charger9 and a generator 10 may be mounted in the master rotorcraft 2 to chargethe battery 8 mounted on each of the slave rotorcrafts 3 while the slaverotorcrafts 3 are coupled to the master rotorcraft 2.

As a practical example, both of the battery charger 9, which is composedof a battery, and the generator 10, which generates an electric power bythe power of the engine 6, can be mounted in the master rotorcraft 2 asshown in FIG. 1 . In this case, the batteries 8 of the slave rotorcrafts3 can be charged using electric power generated by the generator 10, andsurplus electric power can be supplied to the battery charger 9. Then,when the battery charger 9 is charged with electric power, the batteries8 of the slave rotorcrafts 3 can be charged also using the electricpower from the battery charger 9.

Each of the slave rotorcrafts 3 to be charged is coupled to the masterrotorcraft 2 by a detachable structure 11. Therefore, it is necessary tocharge the battery 8 of the slave rotorcraft 3 through the detachablestructure 11. Accordingly, a charging method can be determined accordingto the detachable structure 11.

In an example shown in FIG. 1 , the detachable structure 11 has adetachable arm 11A, and each of the slave rotorcrafts 3 is configured sothat the slave rotorcraft 3 can be separated from and coupled to themaster rotorcraft 2 while in flight and during landing. A method ofattaching and detaching the slave rotorcrafts 3 to and from thedetachable arms 11A of the master rotorcraft 2 is flexible.

FIG. 2 shows the first specific example of the detachable structure 11shown in FIG. 1 .

As a specific example, as shown in FIG. 2 , electromagnets 20A and 20Bcan be attached to at least one of the master rotorcraft 2 and the slaverotorcraft 3. The electromagnets 20A and 20B may control generations ofmagnetic forces. The electromagnets 20A and 20B can be controlled by thecontrol system 5A and the control system 5B. Then, the slave rotorcraft3 can be attached to and detached from the master rotorcraft 2 byswitching ON and OFF the magnetic forces of the electromagnets 20A and20B using control signals transmitted from the control system 5A and thecontrol system 5B to the electromagnet 20A and the electromagnet 20B.

FIG. 3 shows the second specific example of the detachable structure 11shown in FIG. 1 .

As another specific example, as shown in FIG. 3 , a hand 30, which opensand closes by the control system 5A, is attached on the tip of thedetachable arm 11A on the master rotorcraft 2 side, and a coupling shaft31 is attached to the slave rotorcraft 3. Thus, a coupling structure inwhich the hand 30 on the master rotorcraft 2 side holds the couplingshaft 31 on the slave rotorcraft 3 side may be adopted as the detachablestructure 11. In this case, the slave rotorcraft 3 is attached to anddetached from the master rotorcraft 2 by controlling the opening andclosing of the hand 30.

FIG. 4 is an enlarged longitudinal sectional view showing the thirdspecific example of the detachable structure 11 shown in FIG. 1 . FIG. 5is an enlarged longitudinal sectional view showing the docked detachablestructure 11 shown in FIG. 4 .

Yet as another specific example, as shown in FIG. 4 , the detachablestructure 11 includes a motor 40, a ball screw 41, springs 42, rotatingshafts 43, stoppers 44, a female screw 45, a groove 46, and a projection47. Specifically, the ball screw 41 rotated by the motor 40, and thestoppers 44, which respectively rotate around the rotating shafts 43 byexpansion and contraction of the respective springs 42, are attached tothe tip of the detachable arm 11A on the master rotorcraft 2 side.Meanwhile, the female screw 45 and the projection 47 having the groove46 for fitting the stoppers 44 are formed in the slave rotorcraft 3. Thetip of the detachable arm 11A on the master rotorcraft 2 side has aconcave portion 48 which mates with the projection 47 of the slaverotorcraft 3. The tip of the ball screw 41 and the front end or the rearend of each stopper 44 are projected inside the concave portion 48. Thenumber of the stoppers 44 is flexible. For example, two to four stoppers44 can be placed at even intervals along a circle whose center is therotation axis of the ball screw 41.

In a case where the detachable structure 11 has a structure asexemplified in FIG. 4 , the motor 40 is driven to fasten the ball screw41 on the master rotorcraft 2 side to the female screw 45 the slaverotorcraft 3 side to pull the projection 47 on the slave rotorcraft 3side toward the concave portion 48 formed on the detachable arm 11A inthe master rotorcraft 2 side.

As exemplified in FIG. 4 , when the projection 47 of the slaverotorcraft 3 is not inserted into the concave portion 48 at the tip ofthe detachable arm 11A, a convex portion 44A formed at the rear end ofeach of the stoppers 44 protrudes into the concave portion 48 by theelastic force of the spring 42. Meanwhile, as exemplified in FIG. 5 ,when the projection 47 of the slave rotorcraft 3 is inserted into theconcave portion 48 at the tip of the detachable arm 11A, each of thesprings 42 contracts contract due to the end part of the projection 47of the slave rotorcraft 3 being pressed against the respective convexportions 44A formed at the rear ends of the stoppers 44. As a result,the stoppers 44 respectively rotate around the rotating shafts 43, andconvex portions 44B respectively formed at the end parts of the stoppers44 project into the concave portion 48. The convex portions 44B, whichare formed at the end parts of the stoppers 44 project inside theconcave portion 48, fit into the groove 46 formed on the projection 47of the slave rotorcraft 3. Thereby, the slave rotorcraft 3 is held bythe detachable arm 11A of the master rotorcraft 2.

As exemplified in FIGS. 4 and 5 , a typical rotorcraft has stub wings(small wings) 47A. The stub wings 47A are short wings projecting fromthe left and right of the fuselage. Accordingly, when the slaverotorcraft 3 includes the stub wings 47A, at least one of the stub wings47A is used as the projection 47 to allow the stub wings 47A to beinserted into the concave portion 48 on the master rotorcraft 2 side.Similarly, the electromagnet 20B exemplified in FIG. 2 or the couplingshaft 31 exemplified in FIG. 3 may also be attached to at least one ofthe stub wings 47A of the slave rotorcraft 3.

As mentioned above, in the state where the slave rotorcraft 3 is dockedto the master rotorcraft 2, the battery 8 of the slave rotorcraft 3 ischarged by the battery charger 9 and the generator 10 of the masterrotorcraft 2. When the battery 8 of the slave rotorcraft 3 is charged bythe battery charger 9 and the generator 10 of the master rotorcraft 2, acharging method according to a structure of the detachable structure 11is adopted. As concrete examples of a method of charging the battery 8of the slave rotorcraft 3 by the battery charger 9 and the generator 10of the master rotorcraft 2 through the detachable structure 11, thereare a method of power feeding by using a slip ring or the like to formelectric contact points on both the master rotorcraft 2 and the slaverotorcraft 3 and allowing the electric contact points to be mechanicallycontact each other, and a method of wireless power feeding. When thebattery 8 of the slave rotorcraft 3 is charged by a wireless powerfeeding method, wireless devices for the wireless power feeding arerespectively provided in the master rotorcraft 2 and the slaverotorcraft 3.

FIG. 6 shows an example of a structure for supplying electric power tothe battery 8 in the slave rotorcraft 3 from the master rotorcraft 2shown in FIG. 1 . FIG. 7 shows a state where the slave rotorcraft 3 isdocked to the detachable arms 11A of the master rotorcraft 2 shown inFIG. 6 .

As illustrated in FIG. 6 , when the slave rotorcraft 3 has theprojections 47, such as the stub wings 47A, the concave portion 48 forfitting the projection 47 of the slave rotorcraft 3 is formed at the tipof the detachable arm 11A of the master rotorcraft 2, as similarly shownin FIGS. 4 and 5 . Then, an electric supply port 50A and an electricsupply port 50B for supplying electric power are provided to the concaveportion 48 formed at the tip of the detachable arm 11A of the masterrotorcraft 2 and the projection 47 of the slave rotorcraft 3.

More specifically, the electric supply port 50A and the electric supplyport 50B that serve as mechanical contact points e are disposed on theconcave portion 48 formed at the tip of the detachable arm 11A of themaster rotorcraft 2 and the projection 47 of the slave rotorcraft 3 sothat the mechanical contact points may contact each other when the slaverotorcraft 3 is docked to the master rotorcraft 2 by inserting theprojection 47 in the concave portion 48 as exemplified in FIG. 7 .Alternatively, at least one pair of the non-contact electric supply port50A and the non-contact electric supply port 50B for feeding powerwirelessly may be disposed on the projection 47 of the slave rotorcraft3 and the concave portion 48 formed at the tip of the detachable arm 11Aof the master rotorcraft 2.

It is appropriate to apply waterproof treatment to the electric supplyport 50A and the electric supply port 50B. This is due to the electricsupply port 50A disposed on the concave portion 48 and the electricsupply port 50B disposed on the projection 47 being exposed to theweather while the slave rotorcraft 3 is separated from the masterrotorcraft 2.

Each of the stub wings 47A of the slave rotorcraft 3 may have a tiltfunction. In that case, as exemplified in FIG. 6 and FIG. 7 , a harness52 for feeding power is disposed inside a rotation shaft 51 of at leastone of the stub wings 47A to tilt the stub wing 47A. Alternatively,power may be supplied wirelessly between the stub wing 47A and thefuselage of the slave rotorcraft 3. Thereby, even when the stub wings47A are tilted, interference of the stub wing 47A with the harness 52can be avoided. In other words, at least one electric supply port 50Bcan be disposed at the end part of the stub wing 47A having the tiltfunction.

When all of the master rotorcraft 2 and the slave rotorcrafts 3 areunmanned aircrafts, not only is the maneuvering of the master rotorcraft2 and the slave rotorcrafts 3 controlled remotely, but also theattachment and detachment of each slave rotorcraft 3 to and from themaster rotorcraft 2 and the charging of the batteries 8 of the slaverotorcrafts 3 are remotely controlled using the wireless transmissionsof control signals from the controller 4 to the control system 5A of themaster rotorcraft 2 and the control systems 5B of the slave rotorcrafts3, or automatically controlled by flight programs stored in advance inthe control system 5A of the master rotorcraft 2 and the control systems5B of the slave rotorcrafts 3.

As a matter of course, when only the master rotorcraft 2 is a mannedaircraft, a pilot of the master rotorcraft 2 performs the attachment anddetachment of each of the slave rotorcrafts 3 to and from the masterrotorcraft 2 and the charging of the batteries 8 of the slaverotorcrafts 3 by manually operating the control system 5A of the masterrotorcraft 2 and the control systems 5B of the slave rotorcrafts 3.Meanwhile, when at least one of the slave rotorcrafts 3 is a mannedaircraft, a pilot of the slave rotorcraft 3 side performs the attachmentand detachment of each of the slave rotorcrafts 3 to and from the masterrotorcraft 2 and the charging of the batteries 8 of the slaverotorcrafts 3 by manually operating the control system 5A of the masterrotorcraft 2 and the control systems 5B of the slave rotorcrafts 3.

On the contrary, even when at least one of the master rotorcraft 2 andthe slave rotorcrafts 3 is a manned aircraft, the attachment anddetachment of each of the slave rotorcrafts 3 to and from the masterrotorcraft 2 and the charging of the batteries 8 of the slaverotorcrafts 3 are performed by remote operations with wirelesstransmissions of control signals from the controller 4 to the controlsystem 5A of the master rotorcraft 2 and the control systems 5B of theslave rotorcrafts 3, or by automatic controls based on flight programspreviously stored in the control system 5A of the master rotorcraft 2and the control systems 5B of the slave rotorcrafts 3.

FIG. 8 is a top view showing an example where the slave rotorcrafts 3have been connected to the master rotorcraft 2 of the rotorcraft 1 shownin FIG. 1 at different positions.

FIG. 1 shows an example in which the detachable arms 11A are radiallydisposed about the master rotorcraft 2 and in which the slaverotorcrafts 3 are detachably and respectively coupled to the radiallydisposed detachable arms 11A. However, as shown in FIG. 8 , thedetachable arms 11A may be disposed to parallel one another, and theslave rotorcrafts 3 may be detachably and respectively coupled to thedetachable arms. As exemplified in FIGS. 1 and 8 , positions at whichthe slave rotorcrafts 3 are coupled with respect to the masterrotorcraft 2 are flexible.

Besides the above-mentioned configurations, the second main rotors 3Aincluded in all or a part of the slave rotorcrafts 3 may be configuredto be tilted relative to the master rotorcraft 2. The second main rotors3A of the slave rotorcrafts 3 to be tilted may also be tilted relativeto the slave rotorcrafts 3. Alternatively, the second main rotors 3A tobe tilted may be tilted, together with the slave rotorcrafts 3, relativeto the master rotorcraft 2.

FIG. 9 shows an example in which each of the slave rotorcrafts 3 shownin FIG. 1 are tilted relative to the master rotorcraft 2.

As shown in FIG. 9 , tilt structures 60A, which tilt the slaverotorcrafts 3 relative to the master rotorcraft 2, may be provided tothe master rotorcraft 2 or the slave rotorcrafts 3. In this case, thesecond main rotors 3A can be tilted relative to the master rotorcraft 2by tilting the slave rotorcrafts 3 themselves relative to the masterrotorcraft 2.

As a specific example, the slave rotorcrafts 3 rotate relative to themaster rotorcraft 2 by respectively attaching the tilt structures 60A,which have a typical structure for receiving a shaft with a ballbearing, to the detachable arms 11A. Alternatively, as another specificexample, when the slave rotorcrafts 3 include the stub wings 47A asexemplified in FIG. 6 and FIG. 7 , and when the rotation shaft 51 isprovided to each of the stub wings 47A of the slave rotorcrafts 3, theslave rotorcrafts 3 are tilted relative to the master rotorcraft 2 bytilting the stub wings 47A respectively coupled to the detachable arms11A of the master rotorcraft 2.

FIG. 10 shows an example in which the second main rotor 3A of each ofthe slave rotorcrafts 3 shown in FIG. 1 is tilted relative to the slaverotorcraft 3.

As shown in FIG. 10 , each of the slave rotorcrafts 3 may be providedwith a tilt structure 60B which tilts the second main rotor 3A relativeto the slave rotorcraft 3. In this case, the second main rotor 3A tiltsrelative to the master rotorcraft 2 by tilting the second main rotor 3Arelative to the slave rotorcraft 3. Each tilt structure 60B, which tiltsthe second main rotor 3A relative to the slave rotorcraft 3, may also becomposed of known parts, such as a ball bearing and a shaft.

Each of the tilt structure 60A and the tilt structure 60B exemplified inFIG. 9 and FIG. 10 may also be driven by remote control by an operator,by automatic control by a flight program, or by a manual operation by apilot.

(Method of Controlling Rotorcraft)

Next, a specific example of a method of controlling the rotorcraft 1will be described.

As mentioned above, the maneuvering of the master rotorcraft 2 and theslave rotorcrafts 3, the control for attachment and detachment betweenthe master rotorcraft 2 and each of the slave rotorcrafts 3, thecharging of each slave rotorcraft 3 consisting of an electricrotorcraft, and the control of the tilt structures 60A and the tiltstructures 60B are performed according to desired algorithms, such as byremotely controlling the control system 5A of the master rotorcraft 2and the control systems 5B of the slave rotorcrafts 3 based on operationof the controller 4 by an operator, by automatically controllingaccording to flight programs stored in the control system 5A of themaster rotorcraft 2 and the control systems 5B of the slave rotorcrafts3, or by manually operating the control system 5A of the masterrotorcraft 2 and the control systems 5B of the slave rotorcrafts 3 by apilot.

As typical examples, there are flight control for flying the masterrotorcraft 2 and the slave rotorcrafts 3 coupled to the masterrotorcraft 2 to a destination, and detachment control for separatingeach of the slave rotorcrafts 3 from the master rotorcraft 2 at thedestination. That is, after the master rotorcraft 2 arrives at adestination where a mission should be carried out, each of the slaverotorcrafts 3 is separated from the master rotorcraft 2 so that each ofthe slave rotorcrafts 3 operates as the independent second rotorcraft.

By configuring the master rotor craft 2 and the slave rotorcrafts 3 asmentioned above, when each of the slave rotorcrafts 3 is an electricrotorcraft, the consumption of electric power stored in the batteries 8of the slave rotorcrafts 3 is reduced by stopping the rotation of thesecond main rotor 3A and the second tail rotor 3B of each of the slaverotorcrafts 3 while each of the slave rotorcrafts 3 is coupled to themaster rotorcraft 2. That is, the consumption of the electric powerstored in the batteries 8 of the slave rotorcrafts 3 is reduced byflying the slave rotorcrafts 3 only by the lift force of the masterrotorcraft 2 to the destination at which the slave rotorcrafts 3 areseparated from the master rotorcraft 2. Meanwhile, even when the slaverotorcrafts 3 have engines, the consumption of aviation fuel is reduced.

Accordingly, the flight range and flight duration of each slaverotorcraft 3 increase. As a result, a mission requiring a longer timeand/or a mission at a farther location can be performed. In particular,when the slave rotorcrafts 3 electric rotorcrafts, the weaknesses ofelectric rotorcrafts, such as a short flight time and a smalloperational range, can be remarkably improved.

Furthermore, when each of the slave rotorcrafts 3 is an electricrotorcraft in which the second main rotor 3A and the second tail rotor3B are rotated by the motor 7 driven by the battery 8 while the masterrotorcraft 2 is equipped with the engine 6 and at least one of thegenerator 10 and the battery charger 9, the generator 10 or the batterycharger 9 mounted in the master rotorcraft 2 charges the battery 8 usedfor rotating the second main rotor 3A and the second tail rotor 3B ofthe slave rotorcraft 3 during a period when the slave rotorcrafts 3 arecoupled to the master rotorcraft 2. In this case, the flight range andflight duration of each slave rotorcraft 3 are further increased.

Meanwhile, even when all of the slave rotorcrafts 3 and the masterrotorcraft 2 are electric rotorcrafts, equipping the master rotorcraft 2with the charger 9 such a battery storing sufficient electric power,allows the charger 9 equipped on the master rotorcraft 2 to charge thebatteries 8 of the slave rotorcrafts 3 while the slave rotorcrafts 3 arecoupled to the master rotorcraft 2. Thereby, the flight range and flightduration of each slave rotorcraft 3 are further increased.

Even during the period when the slave rotorcrafts are coupled to themaster rotorcraft 2, the second main rotors 3A of the slave rotorcrafts3 may be rotated when an increase in the lift force of the wholerotorcraft 1 including the master rotorcraft 2 and the slave rotorcrafts3 is desired. As a typical example, the second main rotors 3A of theslave rotorcrafts 3 coupled to the master rotorcraft 2 rotates duringstrong winds.

By rotating the second main rotors 3A of the slave rotorcrafts 3 coupledto the master rotorcraft 2 during strong winds, the resistancecharacteristics of the rotorcraft 1 against a strong wind improves.Improving the stability of the rotorcraft 1 in the strong wind allowsthe rotorcraft 1 to fly even in strong winds.

As another example, when the first main rotor 2A of the masterrotorcraft 2 breaks down, the second main rotors 3A of the slaverotorcrafts 3 rotate. Thus, the redundancy of the rotorcraft 1 can besecured. In other words, coupling the slave rotorcrafts 3 to the masterrotorcraft 2 provides for redundancy to the master rotorcraft 2.

When the slave rotorcrafts 3 are coupled to the master rotorcraft 2, thesecond main rotors 3A or the slave rotorcrafts 3 may be tilted relativeto the master rotorcraft 2, and the tilted second main rotors 3A may berotated. As a practical example, as exemplified in FIG. 9 or FIG. 10 ,the flight speed of the rotorcraft 1 is increased by tilting therotating shafts of the second main rotors 3A from the vertical directionto a traveling direction of the rotorcraft 1 like a tilt rotor, androtating the tilted second main rotors 3A while the slave rotorcrafts 3are coupled to the master rotorcraft 2.

Examples of a period when it is desired to increase the lift force ofthe whole rotorcraft 1 include a period when the rotorcraft 1 is takingoff and a period when the rotorcraft 1 is hovering, besides a periodwhen a strong wind is blowing. Thus, when the rotorcraft 1 is taking offor hovering, the second main rotors 3A of the slave rotorcrafts 3 rotatewhile setting the angles of the second main rotors 3A to that allows therotorcraft 1 to achieve the desired lift force. Meanwhile, when therotorcraft 1 is advancing, the second main rotors 3A of the slaverotorcrafts 3 may also rotate while tilting each of the rotating shaftsof the second main rotors 3A of the slave rotorcrafts 3 in the travelingdirection of the rotorcraft 1, as mentioned above. In this caserotorcraft 1 obtains sufficient lift force for a takeoff or hovering ofthe rotorcraft 1 while increasing the flight speed of the rotorcraft 1when the rotorcraft 1 advances.

On the contrary, as mentioned above, the second main rotors 3A of theslave rotorcrafts 3 may be stopped until the slave rotorcrafts 3 areseparated from the master rotorcraft 2, unless conditions in which anincrease of the lift force is desired. That is, the rotorcraft 1 can bedesigned so that the rotation of the first main rotor 2A of the masterrotorcraft 2 provides sufficient lift force even when the rotations ofthe second main rotors 3A of the slave rotorcrafts 3 are stopped. Also,the rotorcraft 1 can be designed so that a sufficient lift force isobtained by rotating the second main rotors 3A of the slave rotorcrafts3 and the first main rotor 2A of the master rotorcraft 2.

When the rotorcraft 1 is designed so that a sufficient lift force isobtained even when the second main rotors 3A of the slave rotorcrafts 3stop rotating, the flight duration and the flight range of each slaverotorcraft 3 increase as mentioned above. In addition, the rotorcraft 1achieves the redundancy. On the contrary, when the rotorcraft 1 isdesigned so that a sufficient lift force is obtained by rotating thesecond main rotors 3A of the slave rotorcrafts 3 and the first mainrotor 2A of the master rotorcraft 2, the lift force required for themaster rotorcraft 2 is reduced.

EFFECTS

As described above, the rotorcraft 1 and the method of controlling therotorcraft 1 allow for at least one slave rotorcraft 3, which includesof a rotorcraft and flies independently, to be attached to and detachedfrom the master rotorcraft 2 which includes another rotorcraft and fliesindependently.

According to the rotorcraft 1 and the method of controlling therotorcraft 1, when a mission requires to be simultaneously operated by aplurality of rotorcrafts, the rotorcraft 1 flies from a takeoff point toa targeted area as a single rotorcraft. On the contrary, aftercompleting the mission, the plurality of the rotorcrafts including themaster rotorcraft 2 and the slave rotorcrafts 3 return as the singlerotorcraft 1 after the mission has been completed. As a result,maneuvering the plurality of the rotorcrafts including the masterrotorcraft 2 and the slave rotorcrafts 3 can be made easy.

In particular, when the slave rotorcrafts 3 are electric rotorcrafts,coupling the slave rotorcraft 3 to the master rotorcraft 2 increases theflight range and flight duration of the slave rotorcrafts 3. Moreover,mounting the generator 10 or the battery charger 9 onto the masterrotorcraft 2 allows each of the electric slave rotorcrafts 3 coupled tothe master rotorcraft 2 to be charged. As a result, the flight range andflight duration of each slave rotorcraft 3 further increases.

OTHER IMPLEMENTATIONS

While certain implementations have been described, these implementationshave been presented by way of example only, and are not intended tolimit the scope of the invention. Indeed, the novel methods and systemsdescribed herein may be embodied in a variety of other forms;furthermore, various omissions, substitutions and changes in the form ofthe methods and systems described herein may be made without departingfrom the spirit of the invention. The accompanying claims and theirequivalents are intended to cover such forms or modifications as wouldfall within the scope and spirit of the invention.

What is claimed is:
 1. A method of controlling a rotorcraft, wherein therotorcraft comprises: a first rotorcraft having a first main rotor and afirst tail rotor; and at least one second rotorcraft having a secondmain rotor and a second tail rotor, the at least one second rotorcraftbeing attachable and detachable to and from the first rotorcraft,wherein the second main rotor of the at least one second rotorcraftrotates electrically, wherein the at least one second rotorcraftincludes a battery providing power to the second main rotor toelectrically rotate the second main rotor, wherein the first rotorcrafthas at least one of a charger and a generator, wherein, during a periodof when the at least one second rotorcraft is attached to the firstrotorcraft while flying, the at least one of the charger and thegenerator of the first rotorcraft charges the battery of the at leastone second rotorcraft to allow the battery to provide the power to thesecond main rotor of the at least one second rotorcraft, and wherein themethod comprises: flying the first rotorcraft, to which the at least onesecond rotorcraft is attached, to a destination; separating the at leastone second rotorcraft from the first rotorcraft at the destination; andhalting the rotation of the second main rotor until the at least onesecond rotorcraft is separated from the first rotorcraft, unless acondition in which a lift force should be increased is satisfied.
 2. Themethod according to claim 1, further comprising rotating the first mainrotor by an engine.
 3. The method according to claim 1, wherein thefirst rotorcraft or the at least one second rotorcraft of the rotorcraftbeing controlled by the method has a tilt structure, the tilt structurehaving a shaft and a ball bearing, the ball bearing receiving the shaft,the tilt structure being configured to tilt the second main rotorrelative to the at least one second rotorcraft or tilt the at least onesecond rotorcraft relative to the first rotorcraft.
 4. The methodaccording to claim 1, wherein both the first rotorcraft and the at leastone second rotorcraft of the rotorcraft being controlled by the methodare unmanned aircrafts.
 5. A method of controlling a rotorcraft, whereinthe rotorcraft comprises: a first rotorcraft having a first main rotorand a first tail rotor; and at least one second rotorcraft having asecond main rotor and a second tail rotor, the at least one secondrotorcraft being attachable and detachable to and from the firstrotorcraft, wherein the second main rotor of the at least one secondrotorcraft rotates electrically, wherein the at least one secondrotorcraft includes a battery providing power to the second main rotorto electrically rotate the second main rotor, wherein the firstrotorcraft has at least one of a charger and a generator, wherein,during a period of when the at least one second rotorcraft is attachedto the first rotorcraft while flying, the at least one of the chargerand the generator of the first rotorcraft charges the battery of the atleast one second rotorcraft to allow the battery to provide the power tothe second main rotor of the at least one second rotorcraft, and whereinthe method comprises: flying the first rotorcraft, to which the at leastone second rotorcraft is attached, to a destination; separating the atleast one second rotorcraft from the first rotorcraft at thedestination; and controlling the second main rotor of the at least onesecond rotorcraft to rotate when the first main rotor breaks down. 6.The method according to claim 5, further comprising rotating the firstmain rotor by an engine.
 7. The method according to claim 5, wherein thefirst rotorcraft or the at least one second rotorcraft of the rotorcraftbeing controlled by the method has a tilt structure, the tilt structurehaving a shaft and a ball bearing, the ball bearing receiving the shaft,the tilt structure being configured to tilt the second main rotorrelative to the at least one second rotorcraft or tilt the at least onesecond rotorcraft relative to the first rotorcraft.
 8. The methodaccording to claim 5, wherein both the first rotorcraft and the at leastone second rotorcraft of the rotorcraft being controlled by the methodare unmanned aircrafts.
 9. A method of controlling a rotorcraft, whereinthe rotorcraft comprises: a first rotorcraft having a first main rotorand a first tail rotor; and at least one second rotorcraft having asecond main rotor and a second tail rotor, the at least one secondrotorcraft being attachable and detachable to and from the firstrotorcraft, wherein the second main rotor of the at least one secondrotorcraft rotates electrically, wherein the at least one secondrotorcraft includes a battery providing power to the second main rotorto electrically rotate the second main rotor, wherein the firstrotorcraft has at least one of a charger and a generator, wherein,during a period of when the at least one second rotorcraft is attachedto the first rotorcraft while flying, the at least one of the chargerand the generator of the first rotorcraft charges the battery of the atleast one second rotorcraft to allow the battery to provide the power tothe second main rotor of the at least one second rotorcraft, and whereinthe method comprises: flying the first rotorcraft, to which the at leastone second rotorcraft is attached, to a destination; separating the atleast one second rotorcraft from the first rotorcraft at thedestination; and increasing a flight speed by tilting the second mainrotor or the at least one second rotorcraft and rotating the second mainrotor, during a period when the at least one second rotorcraft isattached to the first rotorcraft.
 10. The method according to claim 9,further comprising rotating the first main rotor by an engine.
 11. Themethod according to claim 9, wherein the first rotorcraft or the atleast one second rotorcraft of the rotorcraft being controlled by themethod has a tilt structure, the tilt structure having a shaft and aball bearing, the ball bearing receiving the shaft, the tilt structurebeing configured to tilt the second main rotor relative to the at leastone second rotorcraft or tilt the at least one second rotorcraftrelative to the first rotorcraft.
 12. The method according to claim 9,wherein both the first rotorcraft and the at least one second rotorcraftof the rotorcraft being controlled by the method are unmanned aircrafts.